An interest has been increased about a development of an effective system for delivering various therapeutic agents (e.g. peptides, proteins and genetic materials, having high molecular weight as well as chemical drugs and contrast agents, having low molecular weight) into specific organs, tissues, cells, cytoplasm, mitochondria, perinuclear regions and cell nucleus regions. Unlike traditional formulations, site-specific and nano-sized agents have been designed to maximize a bioavailability of the therapeutic agent delivered to a target site, of which therapeutic effect found to increase owing to low side effect thereof. This drug delivery technique has been getting to account for important part among total drug development as high value added technique and utilized increasingly to enhance patients' drug compliance and easy taking of medication.
Endosomal sequestration of a biological agent delivered into a cell is a substantial obstacle, which is removed by destabilization or destruction of an endosomal membrane induced by polymers or monomers having amine, sulfonamide or carboxyl acid. These polymers and monomers improve non-viral gene transfer and cytoplasmic delivery of a chemical drug. In endosomal pH, proton buffering and conformational transition are known to induce instability of lipid membranes or endosomolysis.
Accordingly, the present inventors completed the present invention by preparing a drug delivery carrier of biofunctional substances for getting delivered drug out from endosome to organelle due to proton buffering, as well as for delivering proteins or peptides due to electrostatic attraction to the target site, by using a nucleotide to synthesize a reducing polymer or a non-reducing polymer wherein disulfide bond can be broken well, and obtaining negatively-charged (−) polymer and combining positively-charged (+) protein or peptide to the polymer.
Meanwhile, Korean Patent No. 10-1224004 discloses a polylactic acid derivative compound having a number average molecular weight of 7,000 daltons and less, and a method of preparing the same, protein produced using the same, sustained-release composition for polypeptide or peptide drugs and a method of preparing the same, and has different a technical constitution from reducing or non-reducing polynucleotide polymer for delivering drug of the present invention.